Stroke - Cerebrovascular event Flashcards
What is a stroke?
Clinical syndrome caused by disruption of blood supply to the brain, characterised by rapidly developing signs of focal or global disturbance of cerebral functions, lasting for more than 24 hours or leading to death
What are the 2 main types of stroke?
- Ischaemic stroke (85%)
- Haemorrhagic stroke (15%)
What is meant by ischaemic stroke?
Ischaemic strokes occur when blood supply in a cerebral vascular territory is reduced due to stenosis or complete occlusion of a cerebral artery
What are the 5 TOAST classified causes of ischaemic stroke?
- Large vessel atherosclerosis (50%) - TOAST1
- Intracranial small vessel atherosclerosis (25%) - TOAST3
- Cardio-embolic (20%) - TOAST2
- Other (5%) - TOAST4
- Unknown - TOAST5
Give an example of a large vessel atherosclerotic cause of stroke
Carotid artery stenosis
What are some cardio-embolic causes of stroke?
- Atrial fibrillation
- Endocarditis
- Valvular heart disease
What re some rarer causes of stroke?
Vasculitis
Non-inflammatory vasculopathy
genetic microangiopathies
Parainfectious
Haematological causes
Other
What are some non-inflammatory vasculopathies that can cause stroke?
- Dissection
- Moya-Moya angiopathy
- Metabolic (Fabry disease, homocystinuria)
- Carotid artery web
What are some genetic microangiopathies?
CADASIL, CARASIL, MELAS (SUSAC syndrome is non-genetic)
What are some parainfectious causes of stroke
Covid
HIV
What are some haematological causes of stroke?
- Primary - Antiphospholipid syndrome
- Secondary - Cancer, TTP, IBD
What are some drugs that can cause stroke?
Contraceptives, cocaine, heroin
What are some pregnancy related causes of stroke?
Eclampsia, pre-eclampsia
What are some other embolic causes of stroke (Not cardio-embolic)
Fat embolism
Air embolism
Tumour embolism
What is haemorrhage stroke?
Haemorrhagic stroke occurs when there is rupture of a cerebrospinal artery, with most being due to a primary haemorrhage or subarachnoid haemorrhage
What are some causes of primary haemorrhage in haemorrhage stroke?
Hypertensive, caused by cerebral amyloid angiopathy or rupture of an aneurysm
What are some causes of young stroke (<50)?
Patent foramen ovale or arterial dissection (Identified by TTE with bubble or transcranial doppler)
What are some risk factors for stroke?
- Hypertension
- High BMI
- High fasting glucose
- Air pollution
- Smoking
- Poor diet
- High LDL cholesterol
- Kidney dysfunction
- Alcohol use
- Sedentary lifestyle
Which brain hemisphere is dominant?
Left
What is a common symptom of dominant (left) hemisphere cortical event?
Language dysfunction
What is a common symptom of non-dominant (Right) hemisphere cortical event?
Spatial awareness dysfunction
What are the 2 regions of affected brain tissue in stroke?
Ischaemic core
Penumbra
What is the ischaemic core?
The area of brain which has developed necrosis (Cerebral blood flow < 20%)
What is the penumbra?
The region of tissue around the area with reduced cerebral blood flow, but is getting a supply of O2 and glucose from collateral arteries
This can progress to infarction, but is still salvageable
What is the ischameic cascade?
This is a series of biochemical reactions that are initiated in the brain and other aerobic tissues after seconds to minutes of ischaemia
What is the ischameic cascade that occurs in ischaemic stroke?
- Switch from aerobic to anaerobic metabolism
- Accumulation of lactic acid
- Na/K channel dysfunction
- Na/Ca channel dysfunction
- Mitochondrial apoptotic factor release
What is caused in tissue by Na/K channel dysfunction?
Cytotoxic oedema
What is caused in tissue by Na/Ca channel dysfunction?
- Excitotoxicity
- Degradative enzymes
- Formation of radicals
What changes occur to the blood brain barrier in ischaemia?
- Endothelial swelling
- Inflammatory response leading to astrocytic foot contact being lost from endothelial cells
- No mediated
- Vasogenic oedema starts 4-6 hours after ischaemia, which can lead to haemorrhagic transformation through extravasation of blood
What are the main symptoms of stroke?
Stoke symptoms are typically asymmetrical:
- Sudden weakness of limbs
- Sudden facial weakness
- Sudden onset dysphasia (speech disturbance)
- Sudden onset visual or sensory loss
What is FAST?
- Face - Fallen on 1 side
- Arms - Unable to lift arm
- Speech - Slurred or absent
- Time - Time to call 999
What are the 4 Oxford classifications of stroke?
TACS - Total anterior circulation syndrome
PACS - Partial anterior circulation syndrome
POCS - Posterior anterior circulation syndrome
LACI - Lacunar infarctions
What is total anterior circulation syndrome (TACS)?
This is alarge cortical strokeaffecting the areas of the brain supplied by both themiddleandanteriorcerebralarteries
What are the 3 diagnostic criteria of TACS?
- Contralateral hemiplegia or hemiparesis, AND
- Contralateral homonymous hemianopia, AND
- Higher cerebral dysfunction (e.g. aphasia, neglect)
What is the prognosis of TACS?
Most severe type of stroke with only 5% of patients being alive and independent at 1 year
What is partial anterior circulation syndrome (PACS)?
This is aless severe form of TACS, in which onlypartof theanterior circulationhas been compromised